The president of the UN climate change conference in Copenhagen, Connie Hedegaard, resigned this morning. She is to be replaced by the Danish premier.

"With so many heads of state and government having arrived it's appropriate that the prime minister of Denmark presides," Hedegaard told the 192-nation meeting. "However, the prime minister has appointed me as his special representative and I will thus continue to negotiate the ... outcome with my colleagues," she said.

Rumours circulating in the first week of the 14-day conference suggested that Hedegaard was unhappy with the contents of the so-called "Danish text" a secret negotiating text prepared by rich countries and leaked to the Guardian. It was rumoured that the prime minister, Lars Løkke Rasmussen, would take over to push through that text in the final stages of negotiations.

Hedegaard, who is the Danish climate and energy minister, said the move was merely procedural, and that it was more appropriate for Rasmussen to preside over the final stages of the talks when over 100 heads of state and government will be present. Separately, Hedegaard has been criticised by African nations for favouring rich nations in the negotiations.

"Approximately 115 heads of state and government have decided to participate in COP15 at summit level to close a deal in Copenhagen. This historical will to address the climate challenge is the strongest possible driver for a global agreement," said Rasmussen. "The final negotiations will be tense and strenuous. I have therefore asked minister Connie Hedegaard to continue to negotiate the Copenhagen outcome with her colleagues."

The developments followed a dramatic night during which ministerial negotiations carried on till 5am. US diplomats inserted brackets at numerous places in the negotiating text for the main strand of the negotiations that includes all countries - the long term action plan. This effectively blocked discussions on this negotiating track.

Some observers believe the US wanted to counter moves by developing countries to add their concerns to the text, effectively ensuring that discussions would have to be continued next year.

Another interpretation of the move was that it was a clever way to allow President Obama to come to the negotiations on Friday to "save the talks" by putting back in much of what had been removed.

"[Today's developments] shows that you cannot have a political statement coming out of the two draft texts that have been presented. Any new draft now will come from outside," said one diplomat. "All we can expect now is a bland political statement, and the possibility of the two draft texts going forward to be negotiated next year," said another.

A spokesperson for the British prime minister, Gordon Brown, said that Hedegaard stepping down was not a surprise and had always been planned. He confirmed that Brown, Rasmussen and the Australian prime minister, Kevin Rudd, had discussed the resignation during a three-hour meeting last night. The three had decided that Rasmussen taking over was the right thing to do to "ramp up" the urgency of the talks for the final three days.

A Department of Energy and Climate Change spokesman said: "This is a planned procedural handover to the Danish prime minister ahead at the start of the high level segment. Prime minister Rasmussen has been closely engaged in this process talking to fellow leaders over the past few months, and he will now be taking the negotiations through to the end game. Connie will remain as prime minister Rasmussen's special representative."